blown in insulation calculator?

Anyone know of any good blown in insulation calculators? I need to figure out how much blown in insulation I need to insulate a garage... only 3 and a half walls are to be insulated... (one of them is just plain fiber glass faced batts right now)...

the dimensions of the garage are 20x27x11 with one wall (15ft long) already insulated...

also what is the best type of blowin in to use? I've seen everything from shreaded newspaper treated with fire retarder to ground up cotton like substances